A variety of methods exist in the art for forming porous micro-plastic materials. In particular, the prior art discloses producing a porous product by mixing a salt-type pore-forming agent such as sodium chloride to a resin to form a moulding material, subjecting the moulding material to a moulding process to produce a moulded part and subsequently washing the product to elute or leach the salt-type pore forming agent, thereby forming pores. In a particular variant the resin has a lower melting temperature than the salt-type pore-forming agent and the moulding process involves heating the moulding material to a temperature between that of the melting point of the resin and the salt-type pore-forming agent, moulding the product and subsequently cooling the moulded product until it solidifies.
One drawback of such prior art methods is that when forming highly porous materials, a large amount of pore forming agent is required which, given that the pore-forming agent remains in a particulate form, adversely affects the fluidity of the moulding material when using conventional moulding methods. As a result, such desalting methods have proven unsuitable for forming porous materials having 50% or more by volume of pores.